Modern storage systems are configured to enable providing copies of existing data for purposes of backup, possible restore in case of future data corruption, testing, etc. The copies may be provided with the help of backup and/or snapshot techniques. The use of snapshot techniques greatly reduces the amount of storage space required for archiving large amounts of data. However, there are still situations where it is desirable to delete snapshots or otherwise manage the copies of data in order to deal with storage capacity constraints.
Problems of snapshots storage space management have been recognized in the Prior Art and various systems have been developed to provide a solution. For example:
U.S. Pat. No. 6,584,551 (Huber) discloses a system and method for dynamically expanding a snapshot repository based on predefined parameters. The snapshot repository is monitored for determining if the amount of information stored in the snapshot repository has reached a predetermined volume increase threshold. If a determination is made that the volume increase threshold has been reached, the volume of the snapshot repository is automatically increased. The snapshot repository may also be monitored for determining if the amount of information stored in the snapshot repository has reached a predetermined maximum snapshot repository volume whereupon a warning may be provided.
U.S. Pat. No. 7,159,072 (Kitamura) discloses copy-on-write snapshot processing performed on a storage system in order to produce snapshots of one or more logical volumes in the storage system. The write I/O operations made to the storage system are observed for a certain period of time. Based on observations, an estimate of the size of the storage space required to preserve the snapshot data can be computed. This information can be used to provide sufficient storage space for the snapshot process.
US Patent Application No. 2008/016121 (Revach et. al) discloses an apparatus and a method of managing a snapshot storage pool (SSP) associated with a storage unit of a distributed data storage system. The apparatus includes a logic module and a controller. The logic module is adapted to provide a threshold corresponding to a ratio between a current amount of storage resources used for storing snapshots in the SSP and a total storage capacity defined for the SSP. The controller is adapted to trigger an action which may be effective for managing the SSP in response to the amount of storage resources used for storing snapshots in the SSP crossing the threshold.
US Patent Application No. 2008/281875 (Waida et. al) discloses a method, device, and system for determining when to re-initialize a backing store in a data storage system. When all snapshots associated with a specified backing store are either being deleted or are marked for deletion, the backing store is re-initialized rather than deleting each snapshot independently. The re-initialization of the backing store provides for a quicker way to delete all snapshots than can be achieved by deleting each snapshot independently.
US Patent Application No. 2009/0019251 (Helman et. al) discloses a method for data storage, including configuring in a data storage system a volume storage pool as data storage resources available for allocation of volumes in the data storage system. The method also includes defining a threshold value for the volume storage pool. When the allocation of the volumes causes the threshold value to be crossed, the method includes performing an action for managing the volume storage pool.